1. Field of the Disclosed Embodiments
The present invention relates to a security zipper, a zippered security bag, and a manufacturing method therefor.
2. Description of the Related Art
There is often a need for a bag, or flexible package, which is designed to be closed one time and that: (1) once closed, reopening causes damage, preferably visual damage, to the package; (2) preferably cannot be reopened through the original package opening; and (3) is sealed to prevent pilferage of the contents. Packages with these features are often referred to as “security bags” and are used to contain valuable or important contents such as money transfers for banks and companies responsible for ATMs (automatic teller machines), for crime evidence, or for medical specimens.
Current packages used for these applications typically have a wide strip of pressure sensitive adhesive (PSA) covered with a release liner on a flap of an envelope type package. The package is typically made from a tough polyolefin base film made from resins including LDPE. LLDPE, PP, HDPE, mLLDPE, or blends, co-extrusions, or laminations of any combination.
The user places one or more items in the package, removes the release liner, folds the flap over the opposite package wall and seals the flap to the outer face of the opposite package wall. This is problematic in that wrinkles are often created in the adhesive seal area, particularly when the items are large or heavy or when a flat surface is not available to rest the package on during sealing. It is also difficult to completely seal the sides of the package where the flap is folded. These deficiencies result in gaps that allow access to the interior of the package, presenting opportunities for pilferage, contamination, or leakage of the contents.
Another deficiency is the reliance solely on the adhesive-to-bag film bond to maintain the closure of the bag. It is well known that PSAs when cooled lose their flexibility and bond strength. When reduced to temperatures well below zero Fahrenheit, the PSAs can lose their adhesive properties and can be easily peeled from one or both of the package surfaces, allowing access to the package contents. Once the adhesive returns to room temperature it regains its adhesive properties and the package can be re-closed, leaving no visual signs of tampering.